1. Field of the Invention
The present invention relates to shoes or boots adapted for use in skiing which are of the type essentially formed out of a shell base molded to fit around the foot. Such boots further comprise a shank which is likewise molded in one or more portions to surround the bottom of the leg and is journalled on the shell base.
2. Description of Prior Art
Shoes or boots of the type described above have been known previously and different combinations have been utilized to give relatively rigid shoes or boots good flexional properties without sacrificing their purpose of transmitting the forces exerted on the boot as well as the control of the skis by the skier.
Constructions characteristic of this type of shoe or boot have been described in particular in French Pat. No. 2,096,248 wherein the problem of flexion between the journalled shank and the shell base has been resolved, for example, by providing a spring apparatus installed obliquely between the front of the shank and the top of the shell base. This system functions as a type of shock absorber which is adjustable according the needs of the skier.
Other designs have been developed such as are described in French patent application No. 2,276,851 where the flexion control is achieved by deformation in extension of the lower edge of a portion of the shank cooperating with the upper surface of a rigid shell base during frontward flexional movements of the leg of the skier.
German patent application No. 2,404,447 describes another type of apparatus for controlling the flexion of the shank of the shell base. In this instance, the device in question is provided at the rear of the shank. It consists of an elastic ring simultaneously surrounding a latching zone provided respectively on the shank and on the shell base. The elastic ring is extended as soon as the skier flexes forwardly. As a result, the flexion of the skier is controlled by the ring.
Finally, U.S. Pat. No. 3,848,347 describes a shoe or boot made of a shell and a rigid shank made out of plastic material comprising a vertical slit positioned along the longitudinal axis of the shoe or boot. This slit can be more or less biased to be spread depending on the positioning of a cursor maintaining the edges of this slit thereby allowing for variation of the flexion of the skier's leg as a function of the spacing of the slit obtained.
Furthermore, according to another known design, a shoe having its insertion opening at the rear comprises a shank, having a sort of opening transverse to the longitudinal axis of the shoe at the bottom of the rear portion of the shank. The lower edge of the shank serves as an extendably deformable band during the frontward flexions of the leg of the skier. In this type of system, the elasticity of the band is a function of the nature of the shank material.
However, the above solutions have not been completely satisfactory, in particular because they do not make it possible to actually provide a shank in which the flexional characteristics of the shank are adjustable and which are progressive depending upon the needs of the skier. Furthermore, the various constructions are either too heavy or voluminous, or rely upon interchangeable elements for modifying the flexional characteristics which are inconvenient for the skier.
In certain cases, the shoe or boot is adapted so as to require an opening of the shank along the front of the foot and at the bottom of the leg which results in entry of snow or water into the boot.
Furthermore, such systems require relatively flexible materials although a certain rigidity is also required, if only for laterally holding or securing the base of the leg. Such holding can only be achieved by increasing the thickness of the walls. This unfortunately results in an increase in the weight of the boot. Furthermore, in this type of construction, despite good shock absorption characteristics of the shank, the elastic return properties are very poor.